| 摘要 |
<p>851,056. Automatic temperature control systems. DAYSTROM Inc. Feb. 18, 1957 [April 19, 1956], No. 5420/57. Class 38 (4). A temperature control system for heating means comprises a thermocouple and an opposed voltage reference source, their difference error signal operating control means via a D.C. amplifier which has a four-arm R-C bridge in a feedback loop. The thermocouple 2 and voltage reference source 1 are opposed and at the correct furnace temperature there is no output voltage. With change of temperature an error voltage is applied to the D.C. amplifier, whose output operates a switch 5 controlling the furnace heater 4. The amplifier is provided with current negative feedback by resistor 9 common to the input and output circuits. Differential and integral components are produced across resistor 9 by the lattice network 13, 14, 15, 16, the resistor 17 providing a first-order feedback component. Back-to-back rectifiers 18, 19 are Zener diodes which conduct under the voltage conditions existing during warm-up or cooldown periods, but not during operation involving small variations about the control point. The instrument 12 which monitors output current may be calibrated to read temperature deviation. Figs. 1 and 2 (not shown) provide a theoretical build-up of the lattice network shown in Fig. 3.</p> |
